Drafting table



July 14, 1964 H. N. GROW ETAL 3,140,559

DRAFTING TABLE Filed July 51. 1961 6 Sheets-Sheet 1 l III/I III/ July 14, 1964 H. N. snow ETAL 3,140,559

DRAFTING TABLE Filed July 31. 1961 e Sheets-Sheet 2 y 1964 H. N. GROW ETAL 3,140,559

DRAFTING TABLE Filed July 51, 1961 lmlulm,

6 Sheets-Sheet 3 u y 964 H. N. snow ETAL 3,140,559

DRAFTING TABLE Filed July 51, 1961 6 Sheets-Sheet 4 July 14, 1964 H. N. GROW ETAL 3,140,559

DRAFTING TABLE Filed July 31. 1961 6 SheetsJ-iheet 5 July 14, 196.' GROW ETAL 3,140,559

' DRAFTING TABLE Filed July 31, 1961 6 Sheets-Sheet 6 hggqja fizvenz ews axe/ Www 5 gk gg Qua? A] aid United States Patent "ice 3,140,559 DRAFTIVG TABLE Harry N. Grow and Egon R. Hoenle, Manitowoc, and Roy E. Kanitz, Earl J. Cisler, and Floyd F. Mueller, Two Rivers, Wis, assignors to Hamilton Manufacturing Company, Two Rivers, Wis., a corporation of Wisconsin Filed July 31, 1961, Ser. No. 128,140 28 Claims. (Cl. 45-131) This invention relates generally to drafting tables, and more particularly to a drafting table having an adjustable drafting board.

The primary object of the present invention is to provide a novel drafting table having a drafting board which may be easily raised, lowered and tilted.

It is a further object to provide a drafting table having a novel counterbalancing arrangement permitting the drafting board to be easily manually elevated or lowered.

Another object is to provide a novel drafting table construction having means for effectively holding the drafting board in any desired position of vertical adjustmerit.

Still another object is to provide a novel drafting table assembly wherein the drafting board is tiltable and is provided with means for holding the drafting board in any desired tilted position.

A still further object is to provide a novel drafting table having a tiltable drafting board and means for counterbalancing the tilting movement.

Still another object is to provide a novel drafting table having a counterbalanced tiltable drafting board and means for adjusting the counterbalancing to compensate for loading of the drafting board with such objects as lamps or drafting machines.

Further objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the drawings, in which:

FIGURE 1 is a perspective view of a drafting table embodying the invention;

FIGURE 2 is an enlarged partial view of the structure shown in FIGURE 1 and taken substantially along the line 2-2 of FIGURE 1;

FIGURE 3 is a perspective view similar to FIGURE 1 but taken from the other side of the drafting table;

FIGURE 4 is an enlarged end elevational view of the right end of the structure as shown in FIGURE 1 and the left end as shown in FIGURE 3;

FIGURE 5 is an enlarged sectional view of a portion of the structure shown in FIGURE 4 and taken substantially along the line 55 of FIGURE 4;

FIGURE 6 is an enlarged elevational view partially in section of the rear side of the structure as shown in FIGURE 1 and the left side as shown in FIGURE 3;

FIGURE 7 is an enlarged fragmentary sectional view taken along the line 7-7 of FIGURE 6;

FIGURE 8 is an enlarged fragmentary sectional view taken along the line 8-8 of FIGURE 6;

FIGURE 9 is an enlarged fragmentary sectional view taken subsbtantially along the line 99 of FIGURE 1;

FIGURE 10 is an enlarged fragmentary sectional view taken substantially along the lines 1010 of FIGURES 2 and 9;

FIGURE 11 is a somewhat reduced end elevational view of the structure shown in FIGURES 1 and 3 with the drafting board in an upright position; and

r, 3,140,559 Patented July 14, 1964 FIGURE 12 is a view similar to FIGURE 11, but with the drafting board in the completely lowered and horizontal position.

Generally, a drafting table embodying the invention comprises a supporting structure, which may be in the form of a table, and a drafting board. The drafting board is mounted over the table and is vertically adjustable. For this purpose, the drafting board is mounted on the upper ends of a pair of columns which are carried for vertical movement in end portions of the table. Cooperating with the columns and mounted in the end portions of the table are adjustable counterbalancing means so that the entire weight of the drafting board and columns may be effectively counterbalanced to permit easy raising and lowering of the drafting board by raising and lowering the columns relative to the table. The columns, and consequently the drafting board, may be locked in any position to which they are adjusted by brake means, and the latter may be released by pressure on a brake pedal to permit adjustment.

The drafting board is pivotally mounted on the columns so that it may be readily adjusted to any angle convenient for the draftsman, and the pivotal mounting includes counterbalancing means to permit easy adjustment of the angle of the board. The counterbalancing means is adjustable to compensate for the weight of various objects which may be carried on the drafting board, such as a drafting machine or lamp. The pivotal mounting further includes locking means so that the drafting board may be firmly locked in any position of angular adjustment.

In the embodiment shown in the drawings (see FIG:

in conjunction with the drafting table. A relatively wide upper drawer assembly 20 having a drawer 21 slidably carried therein connects the upper ends of the inner walls 14 of the pedestals 10. A side drawer assembly 22 may be provided, secured between the underside of supports for the upper drawer 20 and the inner wall 14 of one pedestal 10. The space between the side drawer assembly 22 and the pedestal at the opposite end of the table is open at one side of the table to provide leg room for a person sitting at the table, and a panel 23 is provided on the opposite side of the table. The table further includes a table top 25 which is slidably carried in a pair of U-shaped channel members 26 secured to the upper walls 11 of the pedestals 10 and to upper drawer assembly 20, to permit the table top 25 to be moved outwardly from either side of the table.

The drafting or drawing board, shown at 30, is rectangularly shaped and is provided with a molding 31 at each end thereof. The side of the drafting board 30 occupied by the draftsman when using the board is preferably provided with a trough or rack 32 for holding pencils and various drafting instruments. The drafting board 30 is mounted on a pair of support channels 35 which are preferably tapered as shown in FIGURES 1, 2 and 9 and which are secured to the underside of the drafting board 30 as by screws 36.

The drafting board 30 is mounted for pivotal adjustmentso that the draftsman may place the board at any angle convenient to him for the particular work he may be doing. In fact, the board may be adjusted at any angle between a horizontal position, as shown in FIG- URE 12, and a vertical position, as shown in FIGURE 11. The mounting for the board also includes means for locking the board in any adjusted position to rigidly hold the board in such position. The board is preferably pivoted on a horizontal axis parallel to and adjacent the side occupied by the draftsman when using the board, that is, the side at which the trough 32 is located. Since the major portion of the weight of the board is located at the opposite side. of the pivotalaxis, counterbalancing means is provided to permitthe draftsman to adjust the board with a minimum of effort. A draftsman often places objects of substantial weight, such as a drafting machine or lamp, on his board and for that reason the counterbalancing means is adjustable to compensate for the additional weight.

To accomplish the foregoing, a plurality of brake plates or leaves 37 are mounted within each of the support channels 35 as shown in FIGURES 2 and 5. Each of the brake plates 37 is somewhat L-shaped and has a leg or shank portion provided with a pair of spaced holes through which extend tubular rivets 38 secured in the side portions of the support channel 35. The other leg of each brake plate 37 is circular and depends from the drafting board 30 at the end of the support channel 35. At one side of the support channel 35, as shown in FIGURE 5, an anchor plate 39-is mounted on the tubular rivets 38, the anchor plate'39 having a shape substantially the same as the brake plates 37.

Thedepending" leg of each brake plate 37 and the anchor plate 39 have holes therethrough all of which are aligned on'thesame axis to receive a relatively short tubular shaft 41. A short tubular shaft 42 axially aligned with the shaft 41 is mounted in the holes in the brake plates 37 at the other end'of the table as shown in FIG- URE 10;

Two more sets of brake plates 43 are also mounted on the respective tubular shafts 41 and 42, the brake plates 43 being identical to the brake plates 37. The shank portions of the brake plates 43 are positioned to extend downwardly into the upper ends of hollow columns 45 as shown inFIGURES 2 and 5, and are secured between opposite walls thereof by tubular rivets 46. Because the plates 43 of the column 45 shown in FIGURE do not occupy the entire space between the opposite walls carrying the rivets 46, a spacer member 47 is provided to fill out'the space. The plates 43 are positioned in an alternate arrangement with the disks 37 as is shown in FIGURES 5 and 10. The shank portions of the brake plates 37 and 43 are provided with dimples 48 to compensate for the lack of the alternate disks in the area of the shank portions, the dimples 48 on each plate being offset from those on the two adjacent plates so that the dimples on the one plate will rest against a flat portion of the adjacent plate. On the end of the table shown in FIGURES 2 and 10, instead of a spacer 47, an anchor plate 50 is provided to fill out the space in the column 45 at that end, the anchor plate being mounted on the tubular rivets 46 and thus secured to the column. Between the anchor plate 50 and the outermost disk 43 as shown in FIGURE is a washer 51. The anchor plate 50 has a hole therethrough for the tubular shaft 42 and a further threaded hole 53 for a cap screw 54.

From the foregoing it may be evident that the drafting board 30 is pivotally connected to the columns 45 for pivotal movement about the axis of the tubular shafts 41 and 42. To hold or lock the drafting board 30 in any tilted position relative to the columns 45, it should be noted that,.since the anchor plate 39 is secured to the drafting board 30 outwardly of the brake plates 37 and 43, and since the other anchor plate 50 is secured to one of the columns 45 outwardly of the associated brake plates 37 and 43, an outwardly directed force applied to the innermost plates 37 and 43 at each end of the board will cause the brake plates 37 and 43 at the respective ends to be pressed together against the anchor plates 39 and 50 in frictional contact with each other to hold the drawing board 30 in any tilted position.

The anchor plates 39 and 50 are held against outward movement relative to each other by a bar extending through the brake plates and anchor plates at both of its ends. At the end shown in FIGURE 10, the anchor plate 50 abuts against an adjusting plate provided with a hexagonal hub 90, and a washer 91 and nut 92 threaded on the end of bar 80 to hold the anchor plate 50 against outward movement. At the end shown in FIGURE 5, the anchor plate 39 is provided with a hub 82 and abuts against a sleeve 93, the latter being held against outward movement by a washer 94 and a nut threaded on the other end of the bar 80. Cap nuts, such as the nut 96 shown in FIGURE 9, may be applied to the ends of the bar 80 to cover the threads thereon.

The force for pressing the brake plates 37 and 43 intov frictional contact is applied to a pressure pad 56 at the end shown in FIGURE 5 and a pressure pad 57 at the end shown in FIGURE 10. Interposed between the pressure pads 56 and 57 are three tubular shafts 58, 59 and 60 and a toggle assembly 61. The pressure pad 56 is tubular and extends over and is slidable on the inwardly projecting end of the tubular shaft 41 as shown in FIG- URE 5. The pressure pad 56 also extends beyond the side wall of the support channel 35 and engages the innermost brake plate 37. The pressure pad 56 is provided with an internal shoulder and one end of the shaft 60 extends into the pressure pad 56 in engagement With the annular shoulder so that force applied-to the shaft 60 longitudinally thereof will be applied through the pressure pad 56 to the brake plates 37 and 43. The tubular shaft 58 is positioned with one end thereof projecting into shaft 60, and with the other end thereof projecting through the pressure pad 57 and the tubular shaft 42 to the anchor plate 50. The telescoping portion of shaft 60 is staked as at 64 to prevent relative endwise movement of the shaft 58.

The pressure pad 57 is adjustable in length and comprises two members 57a and 57b threaded together to permit the effective length of the pressure pad 57 to be varied. One end of the adjustable pressure pad 57 engages the innermost brake plate 37 on the end of the drafting board opposite from the pressure pad 56. The other end of the adjustable pressure pad 57 is formed with an annular recess to receive a flange on the end of tubular shaft 59. Thus, any force applied to shaft 59 longitudinally thereof will be transmitted to and through the adjustable pressure pad 57 to the brake plates 37 and 43. The shaft 59 encloses the shaft 58.

The toggle assembly 61 is carried by the shaft 58 between the ends of the respective shafts 60 and 59 and constitutes manually operable means for exerting force on the shafts 59 and 60 to apply pressure on the brake plates at both ends of the board. The toggle assembly 61 comprises two toggle brackets 68 and 69, a pair of toggle links 70, and a toggle handle assembly 71, as shown in FIGURES 9 and 10. Each of the toggle brackets 68 and 69 in U-shaped and has a hole through the base of the U for sliding movement on the shaft 58. The bases of the brackets 68 and 69 abut against the ends of shafts 60 and 59and have collars 62 and 63 fixed thereto for locating the ends of the shafts 60 and 59. The arms of the toggle brackets 68 and 69 extend toward each other. Each of the toggle links 70 is formed at one end thereof with a widened portion having a hole 72 therethrough. The other or narrowed end of each of the toggle links 70 is pivotally connected to one of the extending arms of the toggle bracket 69 by pins 73. The toggle handle 71 comprises a pair of bars in face-to-face relation to provide a handle portion 71b and offset end portions 71a extending from the handle portion 71b. The handle portions 71b are secured together as by welding and the offset portions 71a are spaced from each other to fit over the outer faces of the toggle links 70. The inner sides of the offset portions 71a are provided with circular portions 76 of a diameter to fit within the holes 72 in the toggle links 70. The circular portions 76 are positioned in the holes 72 of the toggle links 70 and are pivotally connected to the arms of the toggle bracket 68 by pins 77 positioned eccentrically of the circular portions 76. Thus, on swinging movement of the handle 71b, the brackets 68 and 69 are caused to move away from each other to apply pressure on the brake plates at both ends or toward each other to release such pressure.

The adjustable pressure pad 57 is preferably adjusted so that, when the toggle handle 71 is positioned perpendicular to the axis of the shafts 58, 59 and 60, the toggle brackets 68 and 69 are held to a maximum spacing therebetween by the above described eccentric arrangement, and the pressure pads 56 and 57 apply sufficient pressure to the brake plates 37 and 43 at each end of the drafting board 30 to hold the drafting board 30 in any tilted position thereof. Thus, it is evident that, to tilt the drafting board 30 relative to the columns 45, the toggle handle 71 may be pivoted in either direction toward the axis of the shafts 58, 59 and 60, and then the drafting board 30 may be manually tilted to the desired tilted position, and by returning the toggle handle 71 to the position shown in FIGURE 9, the board is locked in such tilted position.

The counterbalancing of the drafting board 30 is provided by the bar 80 which constitutes a torsion bar. The torsion bar 80 is substantially square or rectangular in cross section throughout the major portion of its length, and one end of the bar extends through a correspondingly shaped opening 81 in the hub 82 of the anchor plate 39. The torsion bar 00 at its other end extends through the adjusting plate 85, as heretofore mentioned, and the adjusting plate 85 has an opening 86 therethrough of the same shape as the bar 80 so that the bar is nonrotatable therein, and the adjusting plate 86 is secured to the anchor plate 50 by a screw 54 which extends through any one of a series of holes 87 in the adjusting plate 85 into a threaded hole 53 of the anchor plate 50. As illustrated in FIGURE 2, the holes 87 are disposed near the periphery thereof on the arc of a circle having its center at the center of the hole 86. The anchor plate 39, as previously described, is secured to the drafting board 30, and the anchor plate 50 is secured to one of the columns 45. It is therefore apparent that any force tending to pivot the drafting board downwardly is opposed by the torsional force produced in the torsion bar 80. If the drafting board 30 is raised to a position such as shown in FIGURE 11, and if the cap screw 54 is then inserted through the hole 87 in the torsion bar adjusting plate 85 which is at the extreme clockwise position thereof as shown in FIGURE 2, it may be seen that the counterbalancing force of the torsion bar 80 will be a maximum. It may further be seen that for any one position of the torsion bar adjustment plate 85, the counterbalancing force produced by the torsion bar 80 is a maximum for the lowered position of the drafting board 30 such as shown in FIGURE 12 and is a minimum for the upright position of the drafting board 30 such as shown in FIG- URE 11. The adjustment of the torsion bar 80 by the torsion bar adjusting plate 85 provides for a matching of the counterbalancing force of the torsion bar 80 to the load upon the drafting board 30. For example, should some relatively heavy object such as a lamp or a drafting machine be placed upon the drafting board 30, the counterbalancing force of the torsion bar 80 may be increased by moving the adjusting plate 85 in a counterclockwise direction as viewed in FIGURE 2 so that the cap screw 54 is positioned through one of the holes 87 in a more clockwise direction as viewed in FIGURE 2. The adjusting plate 85 may be readily turned since its hub 90 is hexagonal.

As heretofore mentioned, the drafting board 30 may be raised and lowered to suit the convenience of the draftsman. To this end, the columns 45 are substantially rectangular in cross section and are carried for upward and downward movement through suitable openings in the top walls 11 of the pedestals 10. As shown in FIG URE 2, the upper end of each column 45 is partially closed by a plate which is secured as by a screw 102 to a bracket 101 extending between opposite walls of the column 45.

The lower end of each column 45 carries a roller 103 (see FIGURE 4) which projects outwardly therefrom to engage a guide 104. Each guide 104 is secured within the lower portion and at one side of each pedestal 10. Each column 45 is further guided by a small roller 105 and a pinion gear 106. Each small roller 105 is carried in a U-shaped support bracket which is secured to one side wall 15 of the pedestal at the upper end thereof as shown in FIGURE 4 and engages one edge of the column. The pinion gears 106 are carried at the respective ends of a tubular shaft 107. The pinion gears 106 are each keyed to the tubular shaft 107 by pins 108 inserted through holes in hub portions of the pinion gears 106, as shown in FIGURE 5. The pinion gears 106 and the tubular shaft 107 are carried in the pedestals 10 by a pair of bearing plates 110. Each bearing plate 110 is secured to the inner side of one of the end walls 13 of the pedestals 10 as by welding. The pinion gears 106 mesh with a pair of gear racks 111 which are secured to the edge of the columns 45 opposite from that engaged by the small rollers 105. Thus, it may be seen that the columns 45 on being elevated and lowered will move between the pinion gears 106 on one edge and the small rollers 105 on the opposite edge, the lower ends of the columns being guided by the roller 103 and the roller guide 104.

The extreme elevated and lowered positions of the columns 45 are respectively determined by an upper stop 113 and a lower stop 114 carried by each column 45 substantially at the lower end thereof as may be seen in FIGURE 4. In the extreme elevated position of the columns 45, the upper stop 113 engages a stop bracket 115 carried at the upper end of the roller guide 104. In the extreme lowered position of the columns 45, the lower stop 114 engages the bottom wall 12 of the pedestal 10. The stops 113 and 114 include resilient members to cushion shock at the extreme elevated and lowered positions thereof.

The load of the drafting board 30 and the columns 45 is effectively counterbalanced by a pair of coiled springs 120. Each coiled spring is located within one of the pedestals 10 and at one end thereof is connected to an adjusting screw 121. Each adjusting screw 121 is anchored by a bracket 122 through the bottom wall 12 of one of the pedestals 10, as shown in FIGURE 4. The other end of each coiled spring 120 is connected to one end of a strap 123. Each strap 123 is anchored to and wound about the inwardly extending hub portion of the pinion gear 106. From FIGURE 4 it will be apparent that, if the drafting board 30 is moved upwardly, the pinion gears 106 will be caused to rotate in a counterclockwise direction as viewed in FIGURE 4 and the straps 123 will be unwound and the tension in the spring 120 decreased. Conversely, it is clear that, if the drafting board 30 is pushed downwardly to move the columns 45 downwardly into the end table assemblies 10, the pinion gears 106 will be caused to rotate in a clockwise direction as viewed in FIGURE 4 and the straps 123 will be wound onto the hub portion of the pinion gears 106 with a consequent elongation of and increase in tension in the coiled springs 120. Because of the larger diameter of the pinion gears 106 relative to the hub portions thereof carrying the straps 123, the change in length of the coiled springs 120 between the extreme raised and lowered positions of the table is relatively small. It may be clearly seen from FIGURE 4 that the counterbalancing force of the coiled springs 120 on the columns 45 and the draft- .1 ing board 30 is easily adjusted by rotation of the exposed head of the adjusting screws 121 at the lower corner of the pedestals 10.

In order that the straps 123 may be accurately guided onto the hub portions of the pinion gears 106, a pair of spring guides 125 are provided. Each spring guide 125 is pivotally carried by a pin 126 on an axis parallel to the axis of rotation of the pinion gears 196. The free end of each spring guide 125 extends slidably through an opening in a link 127 which interconnects coiled spring 120 and strap 123 as shown in FIGURES 4 and 5.

The columns 45 may be locked in any elevated position by means comprising in the present instance a pair of spring brakes 130 each cooperating with a pair of spring brake hubs 131 and 132. Each of the spring brakes 130 is in the form of a spring coiled about the hubs 131 and 132, and when the spring brakes 130 are energized or tightly wound, the brake hub 131 is locked against rotation relative to the stationary hub 132. The hubs 132 are stationary and each is carried in a brake support plate 133 secured to the inner wall 14 of one of the pedestals 10, as by screws 134, as shown in FIGURE 5. Each brake support plate 133 has an opening therethrough to receive one end of the stationary hub 132. The opening and the end of the hub 132 therein are non-circular in form, in this instance having two straight sides so that each hub 132 is prevented from rotating. Each stationary hub 132 is centrally bored to receive a portion of reduced diameter on the brake hub 131, the reduced diameter portion extending through the stationary hub 132 and beyond the brake plate 133 and provided with a washer 137 and a snap ring 138 to retain the hubs 131 and 132 against relative endwise movement. Each rotating hub 131 is mounted on the tubular shaft 107 and is keyed thereto by a pin 140, as shown in FIGURES and 8. The outer diameters of the stationary hub 132 and the rotating hub 131 are substantially equal and contiguously disposed as shown in FIGURE 5, and each spring brake 130 extends over the outer surfaces of both the rotating hub 131 and the stationary hub 132.

To energize each spring brake 130, a brake plate 142 is provided, having the shape illustrated in FIGURE 8. Each brake plate 142 has a circular opening therethrough and is carried on a reduced portion of the end of the rotating brake hub 131 opposite from the end extending through the stationary hub 132. The brake plate 142 is rotatably mounted on the rotating brake hub 131 but is prevented from endwise movement relative thereto by a snap ring 143. Each of the brake plates 142 is provided with an arcuate series of holes 145 arranged for selective insertion of one axially turned end of the spring brake 130. The other end of each spring brake 130 is also axially turned and inserted in a hole 146 in the brake support plate 133. If the brake plate 142 is rotated in one direction, the turns of the spring brake 130 will be tightened to frictionally engage the outer surfaces of both the rotating hub 131 and the stationary hub 132 and thereby prevent relative rotation of the hubs. If the brake plate 142 is rotated in the other direction, the turns of the spring brake 130 will be loosened to permit relative rotation of the hubs.

The spring brakes 130 are self-energizing and are normally maintained in the energized or brake-applied position by means including a pair of coiled springs 150. One end of each of the coil springs 150 is connected to a pin 151 mounted eccentrically on one of the brake plates 142 as shown in FIGURE 8. The coiled spring 150 extends upwardly from the pin 151, and the upper end thereof is connected to a bracket 152 secured to the underside of the top wall 11 of one pedestal 10. The spring brakes 130 are wound in such a direction that the tension of the coiled springs 150 tends to bias the brake plates 142 in a direction to maintain the spring brakes energized. When the spring brakes are energized, the rotating hubs 131 are held against rotation relative to the stationary 8 hubs 132. The rotating hubs 131 are held against rotation, and the tubular shaft 107 and the pinion gears 106 are held stationary. Thus, the columns 45 and the drafting board 30 may be locked in any position.

To permit raising or lowering of the drafting board 30, a spring brake release means is provided, comprising a pair of cables 155 and a brake pedal 156. The brake pedal 156 by the application of a persons foot to the bent extending between the two pedestals 10 and has a bent central portion to provide a lever arm for rotating the brake pedal 155 by the application of a persons foot to the bent central portion. The ends of the brake pedal 156 are journaled in the inner walls 14 of the pedestals 10 as shown in FIGURE 6. Within one pedestal 10, a bell crank member 157 is secured on the end of the brake pedal 156 and 158 is rigidly secured at one end to each plate 157 to extend generally radially of the end of the brake pedal 156 in a direction generally opposite from the direction of the bent central portion. A coiled spring 159 is connected between the outer end of each arm 158 and the bottom wall 12 of the pedestal 10 to bias the bent central portion of the brake pedal 156 upwardly or in a counterclockwise direction as viewed in FIGURE 4.

Each end of each of the cables 155 is formed with a closed loop, and one end of each cable 155 is connected to one of the plates 157 on the same side of the axis of the brake pedal 156 as the bent central portion thereof. The other looped end of each cable 155 is hooked over one of the pins 151 of the brake plates 142. The cables 155 have a length such that when the brake pedal 156 and the plates 157 are positioned as shown in FIGURE 4, the coiled springs 150 maintain the spring brakes in the energized or brake-on position. When the bent center portion of the brake pedal 156 is depressed, the cables 155 are pulled downwardly to rotate the brake plates 142 against the bias of the coiled springs to loosen or slightly unwind the spring brakes 130, so that the spring brakes are operated to the de-energized or brake-01f position. In the de-energized position of the spring brakes, the rotating hubs 131 are free to rotate relative to the stationary hubs 132. Thus, the drafting board 30 and the columns 45 may be manually raised or lowered to any desired position merely by depressing the brake pedal 156. When the spring brakes 130 are deenergized, the previously described counterbalancing means including the coiled springs 120 is effective to counterbalance the weight of the drafting board 30 and the columns 45.

From the foregoing description, it will be apparent that the drawing board 30 may be raised and lowered as well as tilted to various angles. In moving the board vertically or in changing its angle of tilt, the respective counterbalancing means permit easy manipulation of the board by the draftsman. When the board is adjusted vertically or angularly, the locking means for the respective adjustments hold the board in adjusted position.

We claim:

1. A drafting table comprising a table structure having a pair of openings in the upper surface thereof in a spaced apart relationship to each other, a pair of vertically adjustable columns mounted in said table structure and extending vertically through the respective openings, roller means carried on the lower end of each of said columns, a pair of vertically extending roller guides mounted in said table and cooperating with said roller means of said columns to vertically guide the lower ends of said columns, second roller means mounted in said table adjacent said openings and positioned to engage each of said columns on one edge thereof, and means engaging the opposite edges of said columns and controlling vertical movement of said columns, whereby said columns are held in a vertical position during adjustment.

2. A drafting table according to claim 1, in which said controlling means comprises gear racks mounted on said columns, and pinion gears meshing with said racks.

3. A drafting table according to claim 2, in which the 9 pinion gears for the respective columns are both mounted on a shaft and are rotatable therewith, whereby vertical adjustment of the columns is equalized.

4. A drafting table as defined in claim 2, and counterbalancing spring means connected to said pinion gears for biasing said pinion gears to counterbalance the weight of said columns and said drafting board.

5. A drafting table as defined in claim 4, wherein said counterbalancing spring means comprises a pair of coiled springs secured at one end thereof in said table, a pair of straps secured to the other end of said coiled springs, said pinion gears having hub portions and the other ends of said straps being secured to and wound about said hub portions, whereby said coiled springs bias said pinion gears in a direction opposing the weight of said columns and said drafting board.

6. A drafting table as defined in claim 5, wherein said coiled springs are secured to said table by screws to adjust the tension of said coiled springs.

7. A drafting table as defined in claim 5, wherein guides are mounted in said table for holding said straps against twisting under the influence of said coiled springs.

8. A drafting table comprising a table, a pair of columns guided in said table and extending through the upper surface of said table for vertical adjustment, a pair of vertically extending gear racks mounted on said columns, a shaft rotatably mounted in said table, a pair of pinion gears secured on the respective ends of said shaft and meshing with said gear racks, and brake means cooperating with said shaft to hold said shaft against rotation and thereby hold said columns in selected positions of adjustment.

9. A drafting table as defined in claim 8, in which said brake means comprises a pair of brakes mounted on and adjacent the respective ends of said shaft, each brake comprising a hub rotatable with said shaft, a hub secured to said table and held stationary, a coiled spring wound around said hubs and adapted to be tightened on and grip said hubs to hold said shaft against rotation.

10. A drafting table as defined in claim 9, wherein a plate is secured to said stationary hub and to said table, one end of said spring is secured to said plate, a second plate is rotatably mounted on said shaft adjacent said rotatable hub, and the other end of said spring is secured to said second plate, whereby said spring may be loosened and tightened on said hubs by rotation of said second plate in opposite directions.

11. A drafting table as defined in claim 8, wherein said brake means normally is operable to hold said shaft against rotation, and means adapted to be operated by the draftsman is provided for releasing said brake means.

12. A drafting table as defined in claim 10, wherein a spring is connected to said second plate and to said table tending to rotate said second plate in a direction to tighten said coiled spring on said hubs to hold said shaft against rotation, and a brake pedal is pivotally carried by said table, and means is provided connecting said brake pedal to said second plates to rotate said second plates in a direction to loosen said coiled springs on operation of said brake pedal.

13. A drafting table as defined in claim 12, wherein said brake pedal is adapted to be depressed to loosen said coiled spring, and a pair of springs is provided tending to raise said pedal.

14. A drafting table comprising a table structure, a pair of columns extending upwardly from said table structure, a drafting board, means pivotally mounting said drafting board on the upper ends of said columns, means for counterbalancing the weight of said drafting board against pivotal movement, and means operable to hold said drafting board in selected pivoted positions relative to said columns.

15. A drafting table comprising a table structure, a pair of columns extending upwardly from said table structure, a drafting board, and a pair of means pivotally mounting 10 said drafting board on the upper ends of the respective columns, each of said pivotal mounting means comprising two interleaved groups of brake plates, one of said groups being secured to said drafting board, the other group being secured to the upper end of one of said columns, a pivot shaft extending through said groups, and means for pressing the brake plates of both groups together in tight frictional engagement to hold said drafting board in selected pivoted positions relative to said columns, and a pair of supporting channel members secured to said board, said one of said groups of plates having portions mounted in said channels and secured therein, and said other group of plates having portions extending into said columns and secured therein.

16. A drafting board according to claim 15, in which the portions of the brake plates mounted in said channels and extending into said columns are provided with spacing means to hold the brake plates of each group spaced from each other a distance substantially equal to the thickness of the associated brake plates.

17. A drafting table according to claim 15, in which the outermost brake plates of both pivotal mounting means are held against movement away from each other, and each of said pressing means presses the brake plates associated therewith outwardly toward the outermost brake plate, a bar being provided extending from one pivotal mounting means to the other through the pivot shafts thereof and carries abutments on its ends for holding said outermost brake plates against movement away from each other.

18. A drafting table according to claim 17, in which each of said pressing means includes a pressure pad slidably mounted on the pivot shaft associated therewith, said pressure pad being movable outwardly to force the innermost brake plate of the associated groups outwardly and thereby press the brake plates of said associated groups together, a pair of tubes enclosing said bar between said pair of pivotal mounting means and bearing against the respective pressure pads, and manually operable means interposed between said pair of tubes for forcing them away from each other, said manually operable means comprising a toggle device movable to one position to force said tubes away from each other and movable to another position to release the pressure on said tubes, said toggle device comprising a pair of U-shaped members with the base of each U bearing against the end of one of said tubes, a pair of toggle members pivotally connected to the arms of one of said members, and a hand lever having spaced ends pivotally connected to the arms of the other U-shaped member and having circular portions eccentric to the pivotal axis of the lever and rotatably mounted in said toggle members.

19. A drafting table comprising a table structure, a pair of columns extending upwardly from said columns, a drafting board, means pivotally mounting said drafting board on the upper end of said columns on an axis adjacent one edge of said board for movement between a substantially horizontal and a substantially vertical position, and means for counterbalancing the weight of said drafting board comprising a torsion bar disposed on said axis, a first anchor plate secured to said drafting board and to one end of said torsion bar to prevent rotation of said one end of said torsion bar relative to said drafting board, and a second anchor plate secured to one of said columns and to the other end of said torsion bar to prevent rotation of said other end of said torsion bar relative to said column, said torsion bar being adapted to be rotatively twisted on movement of said drafting board toward horizontal position.

20. A drafting table according to claim 19, in which said second anchor plate is adjustably secured to said other end of said torsion bar for rotatively adjusting said torsion bar to increase the torsional resistance thereof and thereby compensate for the weight of objects placed on the drafting board.

21. A drafting table according to claim 19, in which an adjusting plate is secured to said other end of said torsion bar and is adjustably secured to said second anchor plate to secure the latter to said other end of said torsion bar.

22. A drafting "table according to claim 21, in which said second anchor plate has a threaded hole therein radially spaced from the pivotal axis, said adjusting plate has arcuate series of holes radially spaced from the pivotal axis the same distance as said threaded hole, and a screw extending. through a selected one of said series of holes and threaded into said threaded hole.

23. A drafting table according to claim 22, in which said adjusting plate has a non-circular hub whereby said' adjusting plate may be readily rotated when said screw is removed from said threaded hole for inserting said screw through a different one of said'series of holes.

24. A drafting table comprising a table structure, a pair of columns extending upwardly from said table structure, a drafting board, a pair of means pivotally mounting said drafting board on the upper ends of the respective columns on an axis adjacent one edge of said board for movementbetween a substantially horizontal position and a substantially vertical position, each of said pivotal mounting means comprising two interleaved groups of brake plates, one of said groups being secured to said drafting board, the other group being secured to the upper end of one of said columns, and a pivot shaft extending through said groups, a torsion bar extending from one pivotal mounting means to the other and through said pivot shafts, a first anchor plate secured to one end of said torsion bar and providing an abutment for the outermost brake plate of the two groups of one pivotal mounting means, a second anchor plate secured to the other end of said torsion bar providing an abutment for the outermost brake plate of the two groups of the other pivotal mounting means, and releasable means for pressing the two groups of brake plates of each pivotal mounting means outwardly toward the outermost brake plate in tight frictional engagement to hold the drafting board against pivotal movement, said first anchor plate, also being secured to said drafting board and said second anchor plate also being securedto one of said columns, whereby when said pressing means is released and said drafting board is moved toward horizontal position said torsion bar is rotatively twisted to counterbalance the weight of said drafting board.

25. A drafting table comprising a supporting structure, board support means mounted on said structure for vertical movement, a drafting board attached to said board support means, means for holding said board support means in selected vertical positions, and means secured to said supporting structure and said board support means for counterbalancing the weight of said drafting board and said board support means, said counterbalancing means being adjustable to compensate for different loads positioned on the drafting board.

26. A drafting table as in claim 24, wherein said counterbalancing means comprises atension spring, and said adjustment is made by varying the force of said spring.

27. A drafting table comprising a supporting structure, a drafting board mounted for pivotal movement on said supporting structure, and means secured to said supporting structure and to said drafting board for counterbalancing the weight of said board, said counterbalancing means being adjustable to compensate for different loads placed on said board.

28. A drafting table as in claim 27, wherein said counterbalancing means comprises a torsion bar having one end secured to said drafting board and its other end secured to said supporting structure, and said adjustment is made by varying the angular position of one end of said torsion bar relative to its other end.

References- Cited in the file of this patent UNITED STATES PATENTS 968,449 Cogger Aug. 23, 1910 1,956,265 Baker Apr. 24, 1934 1,956,546 Froelick Apr. 24, 1934 2,240,395 Evans Apr. 29, 1941 2,368,748 Doty Feb. 6, 1945 2,646,322 Laxo July 21, 1953 2,694,612 Morrow Nov. 16, 1954' 2,982,050 May May 2, 1961 2,998,672 Sautereau Sept. 5, 1961 FOREIGN PATENTS 1,108,871 Germany Sept. 22, 1959 

1. A DRAFTING TABLE COMPRISING A TABLE STRUCTURE HAVING A PAIR OF OPENINGS IN THE UPPER SURFACE THEREOF IN A SPACED APART RELATIONSHIP TO EACH OTHER, A PAIR OF VERTICALLY ADJUSTABLE COLUMNS MOUNTED IN SAID TABLE STRUCTURE AND EXTENDING VERTICALLY THROUGH THE RESPECTIVE OPENINGS, ROLLER MEANS CARRIED ON THE LOWER END OF EACH OF SAID COLUMNS, A PAIR OF VERTICALLY EXTENDING ROLLER GUIDES MOUNTED IN SAID TABLE AND COOPERATING WITH SAID ROLLER MEANS OF SAID COLUMNS TO VERTICALLY GUIDE THE LOWER ENDS OF SAID COLUMNS, SECOND ROLLER MEANS MOUNTED IN SAID TABLE ADJACENT SAID OPENINGS AND POSITIONED TO ENGAGE EACH OF SAID COLUMNS ON ONE EDGE THEREOF, AND MEANS ENGAGING THE OPPOSITE EDGES OF SAID COLUMNS AND CONTROLLING VERTICAL MOVEMENT 